Comfort-Optimized Demand Response

ABSTRACT

A method of improving a comfort level of a participant in a demand-response program for a facility. The method includes providing a sensor to a participant of a demand-response program, the sensor for sensing a comfort indicator at a facility, the comfort indicator including at least an air temperature; providing instructions for installing the sensor at a facility of the participant; and causing a load-control event communicated to the LCD to be modified, the modification causing the comfort indicator to increase or decrease at the facility, thereby improving the comfort level of the participant in the demand-response program.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 61/704,981 filed Sep. 24, 2012, which is hereby fully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to electrical utility demand response, and more particularly to optimization of demand response so as to minimize consumer discomfort and maximize energy-savings.

BACKGROUND OF THE INVENTION

Utilities need to match generation to load, or supply to demand. Traditionally, this is done on the supply side using Automation Generation Control (AGC). As loads are added to an electricity grid and demand rises, utilities increase output of existing generators to solve increases in demand. To solve the issue of continuing long-term demand, utilities typically invest in additional generators and plants to match rising demand. As load levels fall, generator output to a certain extent may be reduced or taken off line to match falling demand. As the overall demand for electricity grows, the cost to add power plants and generation equipment that serve only to fill peak demand becomes extremely costly.

In response to the to the high cost of peaking plants, electric utility companies have developed solutions and incentives aimed at reducing both commercial and residential demand for electricity. In the case of office buildings, factories and other commercial buildings having relatively large-scale individual loads, utilities incentivize owners with differential electricity rates to install locally-controlled load-management systems that reduce on-site demand. Reduction of any individual large scale loads by such load-management systems may significantly impact overall demand on its connected grid.

In the case of individual residences having relatively small-scale electrical loads, utilities incentivize some consumers to allow them to install demand-response technology at the residence to control high-usage appliances such as air-conditioning (AC) compressors, water heaters, pool heaters, and so on. Such technology aids the utilities in easing demand during sustained periods of peak usage.

Traditional demand-response technology used to manage thermostatically-controlled loads such as AC compressors typically consists of a demand-response (DR) thermostat or a load-control switch (LCS) device. Such DR thermostats, LCS devices, and other known demand-response devices are designed to be used with a wide variety of ducted, thermostatically-controlled heating, ventilating, and air conditioning (HVAC) systems as commonly used in single-family residences in the United States. Typical ducted HVAC systems in the United States utilize distinct and separate thermostatic devices, circulation fan controls, electrical contactors, switches, and so on, that are easily accessible for connection to demand-response devices.

When a DR thermostat, sometimes also referred to as a setback thermostat, is selected as the demand-response device, the DR thermostat generally replaces an existing thermostat. The DR thermostat controls operation of a load by manipulating space temperature or other settings.

When an LCS device is selected as the demand-response device, the LCS device is typically added to the existing HVAC system. The LCS device is most often wired into the control circuit of the electrical load, interrupting power to the load when the load is to be controlled. As such, the LCS device generally functions independently of space temperature.

Because of the temperature-independent nature of most LCS devices, the resultant rise in space temperature during any given load-control event varies from residence to residence such that energy-savings are not optimized, and some utility customers are not comfortable due to an unacceptable rise in temperature.

SUMMARY OF THE INVENTION

Embodiments of the claimed invention provide improvements to demand-response (DR) technology that not only encourage participants of DR programs to continue their participation, but also increase the energy-saving capacity of such programs.

Electrical utility providers typically communicate a load-control event to many participants in a particular geographic area at once. The parameters of the load-control event are typically the same for all participants and their facilities. For example, a load-control event may require that all load-control switches or devices (LCDs) that enable power to an electrical load be limited to a predetermined duty cycle, such as 50%. For a 50% duty cycle, an LCD prevents a load from receiving power for 50% of the time that the utility requires curtailment of energy. For example, this could mean that an LCD prevents an electrical load, such as a compressor of an air-conditioning unit, from receiving power for 30 minutes of every 60 minutes (50% duty cycle).

Although the load-control parameters may be the same for each participant and each facility in a region, the characteristics of each electrical load and each facility will not necessarily be uniform. The result is that for any particular load-control event mandated to multiple participants and facilities, the climatic conditions and perceived comfort levels will vary from participant to participant. This is especially evident for those facilities having under-capacity loads or over capacity loads.

An under-capacity load, such as a relatively undersized AC compressor, may run nearly constantly under extreme conditions, such as hot weather, and its operation will subsequently be more affected by a particular load-control event. For example, preventing an AC compressor from running for 30 minutes of every hour will likely cause a perceivable, and perhaps discomforting, temperature rise within a facility.

On the other hand, an over-capacity load that runs for only a small percentage of any time period, such as an oversized AC compressor, will be less affected by the same load-control event. For example, preventing an AC compressor from operating for 30 minutes of every hour may cause little temperature change at a facility when that AC compressor only typically runs for 10 minutes of every hour.

Those participants having under-capacity loads may be more inclined to over-ride a load-control event, or drop out of the DR program if they experience uncomfortable conditions on a regular basis.

Furthermore, those participants having over-capacity loads are not providing as much energy savings to the DR program.

Embodiments of the claimed invention provide relief to those participants in demand-response programs that experience discomforting climatic conditions during load-control or load-shedding events implemented resulting from under-capacity loads. By providing systems, devices and methods to reduce a comfort indicator level, such as a temperature level, below a discomfort threshold, embodiments of the present invention decrease the possibility of DR program participants overriding a load-control event, or even dropping out of the DR program altogether.

Embodiments of the claimed invention also may capture additional energy-savings for an electrical utility provider by modifying parameters of a load-control event to cause an over-capacity load to operate for less time than a predetermined load-control event would otherwise dictate.

In an embodiment, the claimed invention comprises a method of improving a comfort level of a participant in a demand-response program for a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device in communication with a load of the HVAC system and an electrical utility provider. The method includes: providing a sensor to a participant of a demand-response program, the sensor for sensing a comfort indicator at a facility, the comfort indicator including at least an air temperature; providing instructions for installing the sensor at a facility of the participant; and causing a load-control event communicated to the LCD to be modified, the modification causing the comfort indicator to increase or decrease at the facility, thereby improving the comfort level of the participant in the demand-response program.

In another embodiment, the claimed invention comprises a method of modifying a load-control event to maintain a space temperature at or below a discomfort threshold at a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device in communication with a load of the HVAC system and an electrical utility provider. The method comprises: monitoring a first space temperature with a thermostat having a first temperature sensor; obtaining first periodic comfort indicator data from a second temperature sensor sensing a comfort indicator, the comfort indicator including at least a temperature and obtained during a first predetermined time interval; determining a first profiled interval value for the first predetermined interval value, the first profiled interval value derived from the periodic comfort indicator data; obtaining second periodic comfort indicator data from the second sensor, the comfort indicator including at least a temperature and obtained during a second predetermined interval; determining whether the second periodic comfort indicator data exceeds a sum of the first profiled interval value and a comfort interval differential value; and causing a load of the HVAC system to receive a control signal from the thermostat prior to an expected termination of an off-cycle of a load-control cycle when the second periodic comfort indicator data exceeds a sum of the first profiled interval value and the comfort interval differential value, thereby modifying a load-control event.

In another embodiment, the claimed invention comprises a method of modifying a load-control event for a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device in communication with a load of the HVAC system and an electrical utility provider. The method comprises: determining a comfort profile for the facility, the comfort profile comprising an average profiled interval value; calculating a comfort differential value based on previously-measured climate data; receiving periodic comfort indicator data from a first sensor; and modifying a parameter of a predetermined load-control event communicated to a comfort-optimizing load-control device from an electrical utility provider when the periodic comfort indicator data exceeds a sum of the average profiled interval value and the comfort differential value

In another embodiment, the claimed invention comprises a system for controlling a space temperature of a facility. The system comprises: an electrical load configured to receive power from a power distribution network of an electric utility provider; a control device in communication with the electrical load and configured to selectively cause the electrical load to receive the power from the power distribution network of the electric utility provider; a thermostat having a first controller and a first temperature sensor, the thermostat in communication with the control device of the electrical load and configured to control a temperature of the facility with a first feedback loop that includes the first temperature sensor sensing the facility temperature at a first location; and a comfort-optimizing load control device (LCD) having a second controller and in communication with a second temperature sensor, the LCD configured to influence the temperature of the facility with a second feedback loop that includes the second temperature sensor sensing the facility temperature at a second location.

Other embodiments include devices for modifying a load-control event according to the above-described methods.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:

FIG. 1 is diagram depicting a demand-response system, according to an embodiment of the claimed invention;

FIG. 1 a is a diagram depicting a location of a comfort sensor in a main living space of a facility, according to an embodiment of the claimed invention;

FIG. 2 is a block diagram of a primary feedback loop of a thermostatically-controlled HVAC system, according to an embodiment of the claimed invention;

FIGS. 3 a-3 c are timing diagrams depicting normal operation of a load-control device (LCD), load, and temperature of a facility, prior to, or after, a load-control event, for a first system, according to an embodiment of the claimed invention;

FIGS. 4 a-4 c are timing diagrams depicting normal operation of a load-control device (LCD), load, and temperature of a facility, prior to, or after, a load-control event, for a second system, according to an embodiment of the claimed invention;

FIGS. 5 a-5 c are timing diagrams depicting operation of a load-control device (LCD), load, and temperature of a facility during a load-control event, for a first system, according to an embodiment of the claimed invention;

FIGS. 6 a-6 c are timing diagrams depicting normal operation of a load-control device (LCD), load, and temperature of a facility during a load-control event, for a second system, according to an embodiment of the claimed invention;

FIG. 7 is a graph depicting relative demand reduction and discomfort versus participation population;

FIG. 8 is a graph depicting a change in relative demand reduction and discomfort versus participation population due to the use of the claimed invention;

FIG. 9 is a block diagram of a comfort-optimizing LCD, according to an embodiment of the claimed invention;

FIG. 10 is a flow diagram of a process for modifying a load-control event, according to an embodiment of the claimed invention;

FIG. 11 is a flow diagram of a process for developing a comfort profile, according to an embodiment of the claimed invention;

FIG. 12 is a flow diagram of a process for modifying a load-control event based on the comfort profile of FIG. 11;

FIG. 13 is a block diagram of a secondary feedback loop of the claimed invention, according to an embodiment of the claimed invention;

FIGS. 14 a-14 c are timing diagrams depicting operation of a comfort-optimizing load-control device LCD, load, and temperature of a facility during a load-control event, according to an embodiment of the claimed invention; and

FIG. 15 is a flow diagram of another process for modifying a load-control event based on the comfort profile of FIG. 11.

While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1 demand-response (DR) system 100 of the claimed invention is depicted. In the depicted embodiment, system 100 includes master station 102, electrical power source 104, power distribution network 106, facility 108, and communication network 110. Facility 108 includes meter 112, electrical load 114, control circuit 116, comfort-optimizing load-control device (LCD) 118, comfort sensor 120, local communications system 122, and heating, ventilating, and air-conditioning (HVAC) system 124.

In such a system, master station 102 of an electrical utility typically includes electrical power source 104, from which AC power is transmitted via overhead or underground power distribution lines 106 to facilities or buildings 108. Electrical power source 104 can comprise one or a plurality of power-generating facilities, for example, fossil fuel, hydroelectric, and nuclear power plants.

Master station 102 communicates with devices at facility 108 over long-haul communications network 110. Long-haul communications network 110 may comprise a wireless (depicted) or a wired network, with one-way or two-way communications ability. In a one-way network, master station 102 transmits load-control or load-shedding messages and commands to facility 108, but does not receive data back from facility 108. In a two-way communications system 110, master station 102 transmits such messages and commands, and also receives data from facility 108.

Long-haul communications network 110 may utilize wired or wireless communications, telephonic communications, Internet Protocol-based communications, satellite system-based communications, and the like. Examples of communications systems include 900 MHz FLEX Paging, 154 MHz VHF Paging, wireless mesh network (WMN), and Power Line Carrier (PLC).

Facilities 108 are most often, but are not necessarily limited to, residential or small commercial facilities. Electricity enters facility 108 through power meter 112 and is then distributed to various circuits within facility 108.

As depicted in FIG. 1, in an embodiment, master station 102 communicates over long-haul communications network directly to comfort-optimized LCD 118. In the depicted embodiment, meter 112 comprises a non-communicative device.

In an alternate embodiment, power meter 112 may comprise a “smart meter” that could include energy monitoring and/or communication capabilities, such as automatic meter reading (“AMR”) or advanced metering infrastructure (“AMI”) technologies. In an embodiment not depicted, power meter 112 communicates with master station 102 over long-haul communications network 110. In another embodiment, power meter 112 may communicate with other devices at facility 108 via a short-haul communications network, such as local communications network 122. In such an embodiment, comfort-optimizing LCD 118 may communicate with master controller 102 via power meter 112, rather than directly over long-haul communications network 110. In such an embodiment, meter 112 is configured for long-haul and short-haul communications, while comfort-optimized LCD 118 is configured for at least short-haul, or local communications.

Facility 108, subject to demand response commands by master station 102, typically includes one or more loads 114. Loads 114 may comprise any electricity-consuming, generally high-energy usage device, including compressors of HVAC systems, hot water heaters, pool heaters, and the like. DR systems in accordance with the present invention may be particularly effective with loads 114 that cycle on and off during normal usage, such as compressors.

In an embodiment, power meter 112 is electrically coupled to load 114 to provide electricity to load 114 as controlled by control circuit or device 116. Control circuit 116 in an embodiment comprises an electrical contactor. Electrical contactor may comprise a relay device responsive to a received control signal to selectively connect and disconnect line voltage as supplied by meter 112 to load 114.

Comfort-optimizing LCD 118, in an embodiment, includes switching device 126. Switching device 126 comprises an electrically-operated switching device, which in an embodiment comprises a relay, which may be a normally-closed single-pole, single-throw relay switch. Switching device 126 may also comprise other types of switching devices, including various types of known relays, and switching circuits or modules configured and/or programmed to interrupt a control or power line.

In an alternate embodiment of system 100, comfort-optimizing LCD 118 may be integrated into load 114 and/or its control circuit 116. In one embodiment, comfort-optimizing LCD 118 may be a stand-alone device housed at or in load 114, or may be more closely integrated into load 114 and/or control circuit 116 and share mechanical or electrical components.

In one such embodiment, comfort-optimizing LCD 118 may not comprise a switching device 126, but rather comprises a communications module in electrical communication with control circuit 116, which in an embodiment is co-located with load 114.

Comfort sensor 120 comprises a sensor sensing any one or more of temperature, humidity, air-flow, or another comfort-oriented factor. In an embodiment, comfort sensor 120 comprises a temperature sensor sensing dry-bulb temperature; in another embodiment, comfort sensor 120 comprises a humidity sensor, and senses or otherwise determines humidity and/or wet-bulb temperature (i.e., temperature that considers a humidity level). As HVAC systems 124 generally increase or decrease humidity by design or by default, sensing or otherwise considering a humidity level when determining a comfort level of a conditioned space improves upon a simple temperature measurement by more accurately reflecting a degree of comfort sensed by a person inside facility 108. Basic thermostatic temperature sensors, such as temperature sensor 150, fail to provide this degree of comfort measurement.

In yet another embodiment, comfort sensor 120 comprises any of a combination of a temperature sensor, a humidity sensor, and an air-flow sensor.

An air-flow sensor may be used to simply verify a presence of air flowing in the vicinity of comfort sensor 120, or may be used to calculate a climate indicator, such as a wind-chill or feels-like temperature.

When comfort sensor 120 comprises a temperature sensor, in an embodiment, the temperature sensor includes a resolution of 0.25 degrees F.; in another embodiment, the temperature sensor includes a resolution of 0.1 degrees F.

Although depicted as a wireless device, in alternate embodiments, comfort sensor 120 may be linked to, and communicate with, comfort-optimizing LCD 118 via a hardwire connection.

Further, although comfort sensor 120 is depicted in proximity to a return air duct of HVAC system 124, comfort sensor 120 may alternately be located elsewhere at facility 108, as will be described further below.

Comfort sensor 120 is configured to communicate with comfort-optimizing LCD 118 over local, short-haul communications network 122. Local, short-haul, communications network 122 utilizes, but is not limited to, ZigBee®, Bluetooth®, WiFi®, and various Internet Protocol-based communications protocols.

In an embodiment, comfort sensor 120 comprises a Bluetooth Low Energy 4.0 device with an antenna, a processor or microcontroller, such as an MSP430 or Cortex MO micro controller, a temperature or other climate sensor, and a battery. In an embodiment, comfort sensor 120 also includes a status LED indicating the status of the sensor, and a push button or other switch used to activate, or in some cases, deactivate comfort sensor 120.

HVAC system 124 in an embodiment includes thermostat 128, forced-air unit (FAU) 130, conditioned-air or supply ducting 132, and return-air ducting 134. HVAC system 124 also includes electrical load 114 and control circuit 116 as described above.

Thermostat 128 is communicatively coupled to FAU 130, control circuit 116, and comfort-optimizing LCD 118. In an embodiment wherein FAU 130 comprises a heating element and load 114 comprises a cooling element, such as a compressor, thermostat 128 is coupled to FAU 130 over FAN control line 136 and HEAT control line 138, and to control circuit 116 via comfort-optimizing LCD 118 over COOL control line 140.

In an embodiment, thermostat 128 includes thermostat temperature sensor 150 and thermostat controller 152. Thermostat 128 will generally be located within a conditioned space of facility 108 and will be accessible to a user. In an embodiment, temperature sensor 150 and thermostat controller 152 are integrated into a single unit, such that temperature sensor 150 senses temperature at the location of thermostat 128.

Thermostat 128 may be programmable, non-programmable, digital, mechanical, communicative, and so on. Thermostat 128 may operate on 24VAC, line voltage, or another voltage as needed. In general, it will be understood that thermostat 128 may comprise any number of known temperature-control devices.

FAU 130, in an embodiment, includes FAU controller 154 coupled to controller 152 of thermostat 128, and circulation fan 156. FAU 130 is coupled to supply ducting 132, return-air ducting 134, and load 114.

Under normal operating conditions, that is, when load 114 is not being controlled as part of a load-shedding or load-control event, HVAC system 124 operates to maintain an approximately constant temperature within the conditioned space of facility 108. Switching device 126 of comfort-optimizing LCD 118 is generally in a closed position in the absence of a load-shedding event, allowing communication between thermostat 128 and control circuit 116 and/or load 114.

In general operation, temperature sensor 150 of thermostat 128 senses a space temperature of facility 108 and communicates that information to thermostat controller 152. Thermostat controller 152 compares the sensed space temperature to a temperature set point stored in a memory of thermostat controller 152. If the sensed space temperature is above the temperature set point, allowing for some hysteresis as will be understood by those-skilled-in-the-art, thermostat controller 152 transmits a COOL control signal over COOL control line 140, requesting that load 114 perform a cooling function. In the depicted embodiment, the COOL control signal is received by control circuit 116, which causes load 114 to be powered and begin to operate. In the embodiment wherein load 114 comprises a compressor, refrigerant is supplied to an exchanger in FAU 130.

Thermostat controller 152 also typically supplies a FAN control signal to FAU controller 154, causing circulation fan 156 to force air across the exchanger, thereby cooling the air, forcing it into supply ducting 132, and distributing the cooled air throughout facility 108.

When a space temperature of facility 108 reaches or exceeds the temperature set point as sensed at thermostat temperature sensor 150, thermostat controller 152 ceases transmission of the COOL control signal, and power to load 114 is removed.

A process for heating facility 108 is similar to the cooling process in that thermostat 128 senses a space temperature below a desired set point, and cycles a heating element on and off to maintain a relatively constant space temperature. In an embodiment, load 114 comprises such a heating element, such as in a heat-pump system, water heater, pool heater, and so on.

Consequently, the on/off control of load 114 by thermostat controller 152 in order to maintain a constant space temperature can be modeled by a system having a negative feedback loop.

Referring to FIG. 2, a block diagram of a primary negative feedback control system 170 of HVAC system 124 during is depicted. At function 172, typically accomplished by thermostat controller 152, a temperature set point of thermostat 128 is compared to an actual or measured space temperature of facility 108. The temperature differential or controller error is used by thermostat controller 152 to determine whether to activate load 114. In the case of cooling, if the temperature differential is negative, such that the space temperature as measured by thermostat temperature sensor 150 exceeds the thermostat set-point temperature, thermostat controller 152, the “controller output” comprises a call for cool, or COOL control signal. In the case of a positive temperature differential, a HEAT control signal would be output.

Cooling/heating load 114 is activated, causing an energy transfer, followed by a further cooling/heating process 174. The cooling/heating process 174 may include the cooling and/or heating of forced air from circulation fan 156 and its distribution throughout supply ducting 132, the conditioned space of facility 108, and return-air ducting 134. External “disturbances” may be introduced into the heating/cooling process, affecting the space temperature resulting from the heating/cooling process. Such disturbances may include energy losses of facility 108. As described further below, disturbances may also include the influence of a load-control or load-shedding event.

Thermostat temperature sensor 150 measures the space temperature of facility 108, and the negative-feedback cycle continues such that HVAC system 124 continually strives to maintain a space temperature as close to the thermostatic set point as possible.

Referring again to FIG. 1, when a utility company implements a load-control event, comfort-optimizing LCD 118 causes switching device 126 to open and close, thereby potentially affecting the ability of HVAC system 124 to maintain a space temperature of facility 108 at the thermostat set point temperature. A load-control event will be understood to refer to a period of time during which the utility company intends to control the operation of load 114 by means of data and commands sent to comfort-optimizing LCD 118, or by means of locally stored data and commands. Each load-control event is comprised of multiple load-control cycles. A single load-control cycle comprises an off or shed cycle followed by an on cycle. During the off cycle, load 114 may not be powered on. During the on cycle, load 114 may be powered on.

In an embodiment, a load-control event is initiated by master controller 102 transmitting a load-control command over long-haul communications network 110 to one or more load-control devices in a predetermined geographic region, including comfort-optimizing LCD 118. In an embodiment, a load-control command may include data and instructions to operate switching device at a predetermined duty cycle. For example, at a 50% duty cycle, switching device 126 would remain closed for 50% of the time, such as 30 minutes of every hour. In such an embodiment, without implementing a comfort optimization feature, load 114 would normally be disabled for 50% of the time during the load-control event.

Referring to FIGS. 3 a-c, timing diagrams illustrating operation of cooling load 114 prior to a load-control event are depicted. Load 114 represents a relatively under-capacity load serving facility 108, such as an undersized air-conditioning unit, such that under normal operation, the time that load 114 operates, is powered on, is longer than a time that load 114 is powered off. The time that a load 114 is powered off plus the subsequent time that the load 114 is powered on will be understood to be the “load-cycle length”.

Referring specifically to FIG. 3 a, control logic versus time for switching device 126 of a comfort-optimizing LCD 118. As depicted, switching device 126 remains in the closed position from time T₀ to time T₁₆, in the absence of a load-control event. In other words, comfort-optimizing LCD 118 does not influence the operation of HVAC system 124 (refer also to FIG. 1).

Referring to FIG. 3 b, the on/off operation of load 114 over time is depicted. Load 114 is powered on for the majority of time from start time T₀ to end time T₁₆, including from T₀ to T₂, from T₃ to T₆, from T₇ to T₉, from T₁₁ to T₁₄, and starting again at T₁₅.

Referring to FIG. 3 c, the corresponding effect of the on/off operation of load 114 on a space temperature of facility 108, is depicted. It will be understood that a space temperature represents only one comfort indicator capable of being controlled, and that other comfort indicators as described above may also be controlled and considered. Space temperature at facility 108 is depicted along the vertical axis, while time is depicted along the horizontal axis. T_(sp) indicates a temperature set point of thermostat 128; T_(sp+) indicates the temperature just above T_(sp) that will cause thermostat 128 to transmit a COOL control signal to load 114, causing load 114 to be powered on; T_(sp−) indicates the temperature below T_(sp) that will cause thermostat 128 to cease transmitting the COOL control signal to load 114, thereby causing power to load 114 to be terminated.

From time T₀ to T₂, while load 114 is powered on, the space temperature decreases from T_(sp+) to T_(sp−). At T_(sp+), thermostat 128 sends a COOL control signal to load 114, causing the load to be powered on, and the space temperature falls to T_(sp−) at T₂ as facility 108 is cooled.

At T₂, the space temperature reaches T_(sp−), and thermostat 128 ceases sending the COOL control signal to load 114, causing power to be removed from load 114. From T₂ to T₃, the space temperature rises to T_(sp+) in the absence of cool air derived from load 114.

From T₃ onwards, the cycles are repeated as thermostat 128 cycles load 114 on and off, keeping the space temperature of facility 108 in a range of T_(sp−) to T_(sp+).

As depicted, the time period of T₀ to T₂ is significantly longer than the time period of T₂ to T₃, such that load 114 is operating at a duty cycle above 50%, at approximately a 75% duty cycle (in the absence of a load-control event).

Referring to FIGS. 4 a-c, timing diagrams for a different load 114 serving facility 108 is depicted. Similar to the process described above with respect to FIGS. 3 a-c, thermostat 128 powers load 114 on from T₀ to T₁, then off from T₁ to T₃. A space temperature of facility 108 also ranges from T_(sp+) down to T_(sp−) as thermostat 128 cycles load 114 on and off to keep the space temperature in an acceptable range of T_(sp).

In this situation, load 114 may be considered a relatively over-capacity load. For a single operating cycle, load 114 is on for approximately 20% of the total cycle length, and off for approximately 80% of the cycle length, such that load 114 has a 20% duty cycle in the absence of the influence of comfort-optimizing LCD 118, or another LCD device.

Provided load 114 of FIGS. 3 a-3 c continues to operate without failure, both loads 114 provide the necessary cooling (or heating) capacity.

However, in the presence of a load-control event, the operation of loads 114 is curtailed. Referring again to FIG. 1, during a typical load-control event, and as described briefly above, switching device 126 may be operated at a predetermined duty cycle, during which time control signals from thermostat 128 to load 114 are interrupted, such that load 114 is not allowed to be powered on. When load 114 is a cooling load, such as an air-conditioning compressor, a space temperature of facility 108 tends to rise when load 114 is not powered on; when load 114 is a heating load, a temperature falls when load 114 is not powered on.

As will be described further below with respect to FIGS. 5 a-5 c and 6 a-6 c, for any given switching-device duty cycle (load-control event duty cycle), the amount of temperature change, and in some cases humidity change, in a facility 108 varies depending on a relative size of load 114, as does the resulting perceived degree of discomfort of the occupants.

Referring to FIGS. 5 a-5 c, timing diagrams illustrating operation of system 100, in the absence of a comfort-optimizing feature, having the relatively-undersized load 114 of FIGS. 3 a-3 is depicted.

Referring specifically to FIG. 5 a, responsive to a load-control command received from master controller 102, switching device 126 is actuated according to a predetermined duty cycle. As illustrated, switching device is actuated according to a 50% duty cycle, without regard to local conditions. From time T₀ to T₅, switching device 126 is in a closed position, such that thermostat controller 152 communicates with load 114 as it would in the absence of a load-control event. At T₅, switching device 126 is opened, and left open until time T10.

Referring to FIG. 5 b, load 114 receives commands from thermostat controller 152, and maintains the space temperature within a range of T_(sp+) to T_(sp−), for the time period T₀ to T₅. However, at time T₅, power to load 114 is interrupted due to the opening of switching device 126, and despite a COOL control signal being transmitted from thermostat 128. Load 114 remains powered off from time T₅ to T₁₀.

Referring to FIG. 5 c, the resulting effect on space temperature is depicted. Prior to load 114 being controlled, the space temperature ranges from T_(sp+) to T_(sp−) as during normal operation. At T₅, when power is removed from load 114, the space temperature begins to rise. At T₆, the space temperature has risen to T_(sp+). During normal, uninterrupted operation, a COOL control signal would be received by load 114, and load 114 would power on and begin cooling facility 108. However, during the off-cycle of the load-control cycle, from T₅ to T₁₀, load 114 is not powered on.

Consequently, the space temperature is allowed to rise from T_(sp+) at time T₅ to a high temperature T_(H) at time T₁₀. High temperature T_(H) may be defined by Equation 1 as the set-point temperature, T_(sp), plus ΔT_(H):

T _(H=) T _(sp) +ΔT _(H).  Equation 1

As will be explained further below, high temperature T_(H) may be not tolerable to those occupants of facility 108, particularly heat-sensitive individuals, despite their willing participation in a DR program.

Alternatively Equation 1 could be rewritten in a more general sense as CI_(H=)=CI_(sp)+ΔCI_(H), where CI indicates a general comfort indicator, which may include temperature.

The maximum comfort indicator, or temperature, at which a participant in the DR program will tolerate, or remain comfortable, is defined as the participant's maximum discomfort threshold, DT_(max). Maximum discomfort threshold, DT_(max) may be defined by Equation 2 as the set-point temperature (comfort indicator) T_(sp) plus a comfort indicator differential ΔT_(c):

DT_(max) =T _(sp) +ΔT _(c).  Equation 2

As illustrated by FIG. 5 c, in the instance of relatively-undersized load 114, ΔT_(H)>ΔTc, such that the high temperature T_(H) exceeds the maximum discomfort threshold, DT_(max). Consequently, occupants of facility 108 will experience some discomfort during the load-control event.

Referring to FIGS. 6 a-6 c, timing diagrams illustrating the operation of the relatively over-capacity load 114 of FIGS. 4 a-4 c are depicted.

Referring specifically to FIG. 6 a, the same load-control event having a 50% duty cycle is imposed upon facility 108 and its HVAC system 124.

Referring to FIG. 6 b, from time T₀ to T₅, load 114 is allowed to operate without interruption. At T₅, the off cycle of the load-control cycle begins, and load 114 is not powered on until the beginning of the on-cycle of the next load-control cycle. Load 114 operates from T₅ to T₁₃ to “catch up” and cool facility 108.

Referring to FIG. 6 c, the temperature consequences of the load-control event are illustrated. As expected, from time T₀ to T₅, during the on cycle of the load-control cycle, load 114 operates as needed to maintain the space temperature in the range of T_(sp+) to T_(sp−).

However, when the space temperature rises to T_(sp+) at T7, load 114 is not powered on due to the restriction of the load-control event. Rather, the space temperature rises up to T_(H) at T10. At time T10, load 114 is powered on, and begins to cool facility 108.

In this depiction of the operation of a relatively oversized load 114, the space temperature does not rise as far as the space temperature served by relatively-undersized load 114. In other words the high temperature T_(H) in the case of the under-capacity load 114 (see FIG. 5 c) is higher than the high temperature T_(H) in the case of the over-capacity load 114.

Further, in the case of the over-capacity load 114, the high temperature T_(H) at the end of the off-cycle of the load-control cycle remains below the maximum comfort threshold DT_(max).

Consequently, occupants of a facility 108 served by the under-capacity load 114 will generally experience a greater degree of discomfort as compared to occupants of a facility 108 served by the over-capacity load 114, despite the same load-control event parameters. As will be described below, comfort-optimizing LCD 118 with its comfort-optimizing features may lessen the degree of discomfort for those participants normally above a discomfort threshold, and may even decrease the degree of comfort for other participants normally below the comfort threshold, thereby maximizing energy savings.

Referring to FIG. 7, a graphical illustration of the effect of a given load-control event on a larger population of participants in a typical demand-response program is depicted.

The y-axis of the graph of FIG. 7 represents the population of participants in a demand-response program, while the x-axis represents both a relative demand reduction and a degree of discomfort. The term “demand reduction” refers generally to an amount of time that a load 114 is not allowed to operate, which also equates to an amount of energy not delivered. The more a load 114 is not allowed to operate, the greater the rise in space temperature and humidity, and the greater perceived discomfort. Hence, a greater relative demand reduction generally corresponds to a greater degree of perceived discomfort.

Curve C1, a hypothetical, bell-shaped curve, depicts population versus relative demand reduction and discomfort during load-control. An average demand reduction is represented by mean M and corresponds to a population N. A discomfort threshold DT_(max) corresponds to a participant population of n.

Areas A and C under curve C1 corresponds to those participants whose level of relative demand reduction is less than a discomfort threshold DT_(max). Area B under curve C1 corresponds to those participants whose level of relative demand reduction is large, and who experience climate conditions above discomfort threshold DT_(max).

For the population of participants within Areas A and C, their degree of discomfort is relatively small due to a relatively smaller demand reduction. The degree of discomfort for the population under Area C is particularly low, and generally below a minimum discomfort threshold DT_(min). A utility company and demand-response program provider may assume that participants in the DR program of Areas A and C will tolerate the climatic effects imposed by the program as the level of comfort or discomfort never rises above maximum discomfort threshold DT_(max).

However, the population of participants within Area B experience conditions that exceed their discomfort threshold. If these participants experience these discomforting conditions too often, these participants may notify the utility company of the discomfort, thereby requiring expensive service calls, duty-cycle modification, and so on. Worse yet, a utility company may lose participants in the DR program, lessening the effectiveness of the program.

Methods, devices, and systems of the claimed invention improve the comfort of those normally experiencing conditions above a discomfort threshold, and thereby facilitate the movement of participants from Area B to Area A. Further, because those participants experiencing relatively small demand reductions never approach a discomfort threshold, in an embodiment, the claimed invention “moves” participants from Area C to Area A, thusly obtaining greater energy savings from Area C participants with only minimal discomfort penalties.

Referring also to FIG. 8, Curve C2 represents a revised, hypothetical relationship between participants in the DR program and a relative degree of demand reduction/discomfort level. In this revised, individualized program, participants previously falling into Area B under Curve C1 of FIG. 7 have been migrated to a discomfort level below discomfort threshold DT_(max), such that these participants fall into Area A2.

Further, participants previously in Area C now experience at least a minimum discomfort level DT_(min), and are grouped into Area A2.

Referring again to FIG. 1, the comfort-optimizing features of demand response system 100 that facilitate such migration will be described in further detail.

Referring also to FIG. 9, comfort-optimized LCD 118 in an embodiment includes switching device 126, controller 182, memory 134, communications module 186 with long-haul transceiver 188 and short-haul or local transceiver 190, and power supply 192.

As also described above, switching device 126 may comprise any relay, switching device, or switching function capable of interrupting the control signal of attached load 114 or alternatively directly interrupting power transmission to attached load 114. Or, as also described above, comfort-optimizing LCD 118 may not include a switching device 126, but rather, may include a communications module that communicates with load 114, directing load 114 to power off.

Controller 130 may comprise a processor, microprocessor, microcontroller, microcomputer, or any suitable logic controller capable of performing calculations on measured data, reading from and writing to memory 184, and controlling communications module 186 and its transceivers.

Memory 184 may comprise EEPROM or other suitable non-volatile computer readable memory capable of storing data including current, voltage, or power data. Alternatively, memory 184 may also comprise volatile computer readable memory, or a combination of volatile and non-volatile computer readable memory in certain embodiments. Such embodiments include non-transitory, computer-readable storage mediums storing instructions to be implemented by controller 182 and LCD 118.

Communications module 186 includes long-haul transceiver 188 and short-haul transceiver 190. Long-haul transceiver 188 in certain embodiments comprises both a transmitter and receiver for transmitting and receiving data, and in other embodiments comprises a receiver for receiving data only. Long-haul transceiver 188 can utilize a wide variety of communication methods for communicating over long-haul communications networks, including communications network 110. In an embodiment, transceiver 188 comprises a radio-frequency transceiver. Long-haul transceiver 188 may utilize any suitable communications format and medium, including the long-haul communication interfaces and protocols discussed above with respect to FIG. 1.

Short-haul transceiver 190 in certain embodiments comprises both a transmitter and receiver for transmitting and receiving data, and in other embodiments comprises a receiver for receiving data only. Short-haul transceiver 188 can utilize a wide variety of communication methods for communicating over short-haul or local communications networks, including local communications network 122. In an embodiment, transceiver 190 comprises a radio-frequency transceiver. Short-haul transceiver 190 may utilize any suitable communications format and medium, including the communication interfaces and protocols discussed above with respect to FIG. 1. In an embodiment, short-haul transceiver 190 is configured to communicate with comfort sensor 120.

In another embodiment, comfort-optimizing LCD 118 may not include a short-haul transceiver 190. In such an embodiment, comfort-optimizing LCD 118 may receive local data directly or indirectly from local sensors through a hard-wire connection to LCD 118 and controller 182. One such local sensor includes comfort sensor 120.

Power supply 192 may be any power supply capable of conditioning and supplying power to components of comfort-optimizing LCD 118.

In general operation, and as described briefly above, during a load-control event, master controller 102 transmits load-control commands to one or more systems 100. In an embodiment, the load-control commands may include a set of load-control data and/or commands relating to a comfort-optimizing function specific to a particular, individual comfort-optimizing LCD 118, or may include a same set of comfort-optimizing data and/or commands to be used by a group of comfort-optimizing LCDs 118.

In other embodiments, load-control data and commands may not include comfort-optimizing information, but rather, may include only “standard” load-control information, such as a desired duty cycle. In such an embodiment, comfort-optimizing LCD 118 may modify received load-control data and commands based on locally-stored, pre-programmed software, firmware or data or historical data gathered by comfort-optimizing LCD 118.

In an embodiment, comfort-optimizing LCD 118 measures, stores, and processes current and historical comfort-related data to determine whether and how to modify a predetermined load-control event. In another embodiment, current and historical comfort-related data is transmitted from comfort-optimizing LCD to master controller 102 for processing and determination of any modifications. Such modifications may result in reducing a discomfort level to below a maximum discomfort threshold, such as DT_(max), or may result in increasing a discomfort level toward DT_(min) (refer back to FIGS. 7 and 8).

Referring to the flow diagram of FIG. 10, an embodiment of a process for modifying a load-control event is depicted.

At step 202, a demand-response program participant is identified as a candidate for comfort-optimizing a load-control event. In an embodiment, a utility company identifies a participant of an existing demand-response program as a candidate for comfort-optimization. Such identification may be accomplished by receiving notice that a participant is unhappy or dissatisfied with the demand-response program. This includes consumers advising a utility company or service provider that during a load-control event the space temperature, or other comfort indicator, in their facility 108 exceeds their desired comfort level.

In another embodiment, identification of the comfort-optimization candidate may comprise an installer of demand response equipment receiving information for a utility company or other source identifying the candidate.

In another embodiment, a number of candidates for receiving a comfort sensor 120 are identified for the purposes of sampling a population of program participants. An identification process may include randomly, or purposely, selecting a predetermined percentage of participants meeting a criteria, such as a similar geographic area, to receive sensors 120. Such selected participants would ideally be representative of the target population of participants, and would not be selected based on actual or expected discomfort levels, but rather would be selected so as to obtain data representative of the target population of participants. In an embodiment, a target population of participants might be participants having similar facility ages and/or characteristics, such as a particular neighborhood or other geographic region might have. Data gathered from the sampled target population could be transmitted back to a master controller from the LCD and be used to set comfort differentials for the target population, as discussed further below.

At step 204, comfort sensor 120 is provided to the previously-identified candidate, a demand-response participant. In an embodiment, comfort sensor 120 is provided to the participant by forwarding comfort sensor 120 to the participant for installation. “Forwarding” may include mailing or posting the sensor to the participant, having an installer of an outside LCD 118 leave the comfort sensor 120 at the facility 108, possibly outside facility 108, such as on a door knob, or by other means. Instructions for installing comfort sensor 120 may also be provided.

In another embodiment, comfort sensor 120 is provided by a party installing comfort sensor 120.

At step 206, comfort sensor 120 is installed. Comfort sensor 120 may be installed by the demand-response participant, by a utility company representative, by a third-party installer, or by another. Installation by the demand-response participant or occupant of facility 108 provides a particularly cost-effective means for getting comfort sensor 120 installed. On the contrary, known methods of limiting a temperature rise during a load-control event when an indoor demand-response thermostat generally require entrance to facility 108 by a trained service technician.

In an embodiment, a comfort-optimizing LCD 118 is installed for every participant in a demand response program, but comfort sensors 120 are provided only when needed. In another embodiment, a known LCD lacking the comfort-optimization features of the claimed invention is initially installed, and is replaced by a comfort-optimizing LCD 118 and sensor 120, after the participant is identified as a comfort-optimization candidate. In such an embodiment, step 204 may include providing a comfort-optimizing LCD 118 and step 206 may include installing a comfort-optimizing LCD 118. In yet another embodiment, a known LCD is modified to include the comfort-optimization features of the claimed invention.

The location of comfort sensor 120 may vary. Referring also to FIG. 1 and FIG. 1 a, in an embodiment comfort sensor 120 is attached to return-air ducting 134. In an embodiment, the entirety of comfort sensor 120 may be attached to an exterior of ducting 134 by means of an adhesive, such as foil tape. In an embodiment, comfort sensor 120 is a relatively small, thin sensor, approximately 1″ wide by 2″ long. In another embodiment, a portion of comfort sensor 120 is inserted through a hole in ducting 134, thereby exposing comfort sensor 120 to return air in return-air ducting 134. Such an embodiment may be useful for those comfort sensors 120 including an air-flow sensor. In yet another embodiment, comfort sensor 120 may be inserted, completely or partially, at a grille, register 135, or vent of ducting 134, as depicted in FIG. 1 a.

While sensing air conditions return air ducting 134 provides a degree of assurance that the measured conditions reflect the conditions of the conditioned space of facility 108, in other embodiments, comfort sensor 120 may be placed in a location other than the return-air ducting 134. Such locations may include locating comfort sensor 120 in or at supply ducting 132, or elsewhere within the conditioned space of facility 108. In an embodiment the location of comfort sensor 120 may be different from the location of temperature sensor 150 of thermostat 128.

Installation instructions provided to a participant or installer may include instructions for selecting a location of comfort sensor 120.

At step 208, a comfort profile is determined. The comfort profile reflects, at least in part, historical comfort indicators of facility 108. The comfort indicators may include temperature, humidity, air flow, and other parameters or indicators as sensed by remote comfort sensor 120. As described in greater detail below with reference to FIG. 11, the comfort profile of a facility 108 is used to modify parameters of a load-control event.

At step 210, a load-control event is initiated. As described above, the load-control event may include data and commands causing comfort-optimizing LCD 118 to cycle switching device 126 on and off, thereby affecting operation of load 114.

At step 212, the load-control event is modified based on the determined comfort profile. The modification, or comfort optimization, may comprise a reduction in a discomfort level, such as described below with respect to FIGS. 12 and 14, or may comprise an increase or boost in discomfort level as described below with respect to FIG. 15

Referring to the flow diagram of FIG. 11, an algorithm 208 for developing a comfort profile for facility 108 is depicted.

At step 220, comfort sensor 120 periodically senses comfort indicators and provides this periodic sensed data to comfort-optimizing LCD 118. In the case of comfort sensor 120 being wired to comfort-optimizing LCD 118, LCD 118 may poll comfort sensor 120 periodically to obtain data. In the case of comfort sensor 120 comprising a wireless device transmitting over local communications network 122, comfort sensor 120 may collect data over a predetermined time period, then periodically transmit the collected data to comfort-optimizing LCD 118 for analysis. In an embodiment, comfort sensor 120 collects and reports data every minute.

At step 222, the validity of the periodic comfort data is verified. In an embodiment, periodic data is verified based on the presence of air flow at the time that the comfort data was sensed. The presence of air flowing provides an indication that the sensed comfort data is indicative of the conditions of facility 108. If air is not flowing in the vicinity of comfort sensor 120, a comfort indicator, such as temperature, may only be indicative of the conditions at sensor 120, rather than elsewhere. Such may be the case where air is not flowing in return ducting 134, and a temperature of the stationary air in ducting 134 rises or falls in the absence of renewed cooled or heated air from FAU 130.

In an embodiment, data is valid if circulation fan 156 is powered on; in another such embodiment, an air flow sensor of comfort sensor 120 senses air flow at comfort sensor 120, such as in ducting 134, in ducting 132, or elsewhere.

In another embodiment, data is valid if load 114 is powered on at the time that comfort sensor 120 senses a comfort indicator. In such an embodiment, load 114 may not typically be operated in the absence of air flow, such that air flow may be implied through verification of the operation of load 114.

In yet another embodiment, data is valid if either a circulation fan 156 operation is verified to have operated for a minimum amount of time (via actual air-flow detection or powering of the fan) or load 114 is verified to have operated for a minimum amount of time. In an embodiment, the minimum amount of time may be predetermined, and may range from zero minutes to 10 minutes. Requiring a minimum run time allows duct or space air conditions and comfort sensor 120 time to adjust and more accurately represent actual indoor temperatures within a space of facility 108.

Air flow may not be present when circulation fan 156 is not powered on, which may be the case when HVAC system 124 is not conditioning the air, such as when a temperature is within an acceptable range of a temperature set point, when system 124 or fan 156 is turned off, or otherwise not functioning.

In an embodiment, verification may also require sensing whether system 124 was in a cooling or heating mode. In one such embodiment, if load 114 is used for cooling, and another, uncontrolled load, such as a furnace heating element is used as a heating supply/load, data is only verified when HVAC system 124 is in a cooling mode. Such verification may be accomplished by sensing a temperature change in ducting 132 or 134, or by confirming operation of load 114.

Verification of comfort data may be accomplished in other ways, including analysis of historical and current climate data collected by comfort sensor 120 or another source, and in other ways not limited to those described above.

If comfort data is not valid, additional data may be collected at step 220.

If comfort data is valid, in an embodiment, at step 224, data collection continues periodically over a predetermined interval. Valid data is saved into memory for further analysis. In an embodiment, a first interval may comprise any predetermined period of time, including, but not limited to, an hour, several hours, a day, or other such interval.

At step 226, the number of valid periodic comfort indicator values is verified to be at or above a minimum predetermined value. If less than a minimum number of valid data readings is available, the resulting comfort profile may be inaccurate. Consequently, if the number of valid data readings is below a minimum, the algorithm reverts to step 220, and additional data is collected.

If the minimum is met, then at step 228, an average value for an interval is determined. This determination may be made by a processor or controller 182 of LCD 118, or may be made by a remote processor. An average value for one or more comfort indicators may be saved. An average value may comprise an average dry-bulb temperature value for the interval, an average wet-bulb temperature, average heat index or humidex, average felt air temperature (a.k.a. wind chill), average humidity, or other such averaged value.

At step 230, in an embodiment, a type of day is determined. In an embodiment, determination of the type of day may simply comprise determining the day of the week based on date. In another embodiment, type of day may include some other classification, in some cases based on weather patterns (e.g., “hot” day as compared to historical averages), energy costs, and so on.

In another embodiment, step 230 may also determine another relative time frame, such as relative time of day, including morning, afternoon, night, and so on. In yet another embodiment, step 230 is not performed. Rather the interval previously identified at step 224 is sufficient.

At step 232, a previous, historical corresponding average interval value is updated based on the current average interval data determined at step 228, and saved into memory, such as memory 184 of comfort-optimizing LCD 118. In an embodiment wherein an interval comprises an hour of a particular day of the week, the previous interval data for that hour of that day of the week may be updated.

In an embodiment, the profiled interval value, meaning the saved, historical average comfort-indicator value for a particular time interval, comprises a weighted average, such that the profiled interval value is updated to include the current average interval value from step 228, but not necessarily replaced by the current average interval value, so as to minimize the impact of a single data point. In one such embodiment, the current average interval value is multiplied by a weighting factor and averaged into the profiled interval value per Equation 5 below:

PIV_(I) =W·CIV_(I)+(1−W)PIV_(I-1)  Equation 5

where PIV₁ is the profiled interval value at interval I, W is a weighting factor, CIV_(I) is a current interval value at interval I, and PIV_(I-1) is the profiled interval value at interval I−1 (the previous profile interval value).

In one embodiment, weighting factor W ranges from 0.01 to 1.0; in another embodiment, weighting factor ranges from 0.1 to 0.5; in another embodiment, weighting factor W is 0.125.

Such determined or calculated average comfort values for a series of intervals may be compiled or saved in a memory of LCD 118 to form a comfort profile for a longer time period, such as a daily comfort profile, weekly comfort profile, and so on. In an embodiment, a comfort profile comprises an average comfort value for each hour (interval) of each day of the week, or series of 168 comfort values, saved in a memory device, such as memory 184 of comfort-optimizing LCD 118, or a remote memory, such as a memory located at master controller 102 or elsewhere. In an embodiment, each profiled comfort value is a temperature value.

In an embodiment, a month and/or season of the year may also be determined and saved as part of the comfort profile.

The determined comfort profile provides an indication of a comfort level experienced at facility 108 over a period of time. In an embodiment, comfort sensor 120 senses both temperature and humidity, and a processor, such as, but not limited to, controller 182 calculates an average temperature, relative humidity, and heat index for each interval of an hour, such that the comfort profile comprises a data array of average comfort values, each average value corresponding to an identified period of time.

Once a comfort profile has been established for a particular facility 108, a historical perspective reflecting the climatic preferences of the demand-response participant is known and may be considered when modifying a load-control event for that particular facility 108. In an embodiment, a comfort profile of a facility 108 may indicate that the demand-response participant prefers to maintain an average dry-bulb temperature of 70° F. and a relative humidity of 40% at all times. In another embodiment, another comfort profile of another facility 108 may indicate that the demand-response program participant allows the average dry-bulb temperature to range from 72° F. during evening, nighttime, and weekend hours, to 76° during daytime, weekday hours.

In an embodiment, when an former occupant and DR participant leaves facility 108, and a new occupant moves into facility 108, a new comfort profile may be determined. Determining that a former occupant has vacated and a new occupant arrived, and determining a new comfort profile, may comprise steps of a method of the present application

As described with respect to step 212 of FIG. 10, the comfort profile can then be used to modify a load-control event. In an embodiment, modification of the load-control event by comfort-optimizing LCD 118 ensures that a discomfort threshold DT_(max) is not exceeded. In another embodiment, modification of the load-control event by comfort-optimizing LCD 118 boosts conditions in facility 108 closer to a discomfort threshold DT_(max), and in some cases, at least to a minimum discomfort threshold DT_(min).

Referring to the flow diagram of FIG. 12, an embodiment of an algorithm 212 a (an algorithm defining an embodiment of step 212 of FIG. 10) for modifying a load-control event to maintain a comfort indicator below a maximum comfort threshold DTmax is depicted and described. For simplicity, algorithm 212 a refers to the sensed comfort indicator as temperature, though it will be understood that other comfort indicators, including those discussed above, may be used.

At step 240, an off or shed cycle of a load-control cycle of a load-control event begins.

At step 242, a recent validated periodic comfort indicator (temperature), is compared to the sum of a profiled interval value of the comfort profile for facility 108 plus a comfort differential, AC. The profiled interval value is for a particular interval or time period of the comfort profile, for example, the profiled interval value may be 72° F. for the hour-long Monday interval starting at 8:00 am and ending at 9:00 pm. The time range of the interval of the comfort value used for comparison includes the time of the periodic comfort indicator, for example, the Monday 8:00 am to 9:00 am interval corresponds to any periodic data obtained and validated on a Monday sometime between 8:00 am and 9:00 am. Recalling the process of FIG. 11, the recent periodic comfort value, which may be a temperature, may comprise the most current, valid data available. The recent periodic comfort value may comprise a single, sensed data point, or may comprise an average, including a weighted average value.

The profiled interval value plus the comfort differential define a maximum discomfort threshold for a predefined interval I, DT_(Imax), for facility 108 and its demand-response program participant:

DT_(Imax)=PIV_(I)+ΔC_(I)  Equation 6

where PIV_(I) is a profiled interval value at interval I and ΔC_(I) is a comfort differential for interval I.

A comfort differential ΔC may be constant or dynamic, may be determined and/or provided by a utility company, may be determined or modified by LCD 118, may be unique to a particular facility 108, may be the same as other facilities 108 for a particular region or category, may be determined in whole or in part by recent or historical local obtained by comfort-optimizing LCD 118.

In an embodiment, AC is simply a predetermined dry-bulb temperature differential, such as 3.5° F. as determined by a utility company and sent to multiple LCDs 118 in a predefined geographic region. In such an embodiment, a maximum discomfort threshold for all demand-response program participants is determined to be 3.5° F. above their profiled interval for any particular interval. In such an embodiment, while the comfort differential is the same for all participants, the maximum discomfort threshold, DT_(max), will vary from facility to facility based upon the climatic preferences of each program participant.

In an embodiment, comfort differential ΔC is determined based on weather conditions. For a cooling load 114, a comfort differential ΔC may be increased above a standard or baseline value based on weather conditions that include extreme high temperatures or high relative humidity.

In another embodiment, comfort differential ΔC may be determined based on desired demand reduction goals. Recognizing the need for a higher-than-average demand reduction, a comfort differential ΔC may be increased above a baseline value to meet a calculated demand-reduction target.

In another embodiment, comfort differential ΔC is a predetermined value as agreed upon by an individual participant upon entering the demand response program.

Recalling that an objective of comfort-optimizing LCD 118 is to prevent DR program participants from overriding a load-control event or even leaving the program, by limiting discomfort of the participant, if at step 242, when the periodic temperature exceeds the profiled interval value of the comfort profile plus a comfort differential, at step 244, the shed cycle is not implemented, or is skipped. In other words, comfort-optimizing LCD 118 does not disable operation of load 114, which may normally be accomplished by opening switching device 126.

If at step 242, the periodic comfort indicator value (temperature) is not greater than a profiled interval value plus the comfort differential, at step 246, the process waits until a next periodic temperature is available.

At step 248, the next periodic temperature is compared to the sum of the profiled interval value plus the comfort differential (maximum discomfort threshold). If the next periodic temperature is not greater than the maximum comfort threshold, DT_(Imax), steps 246 and 248 are repeated.

When the next periodic temperature exceeds the maximum comfort threshold, at optional step 250, a load protection time is checked. This is to prevent short-cycling of load 114. When load 114 comprises a compressor of an air-conditioning system, allowing the compressor to run for a minimum run or protection time prevents damage to the compressor.

At step 252, if a load protection time has not passed, the process waits until the minimum load time has elapsed.

At step 254, the off or shed cycle is ended, allowing load 114 to be powered on as requested by thermostat controller 152.

Consequently, from a system control perspective, space temperature, or another comfort level indicator, is controlled during a load-control event by the interaction of two different controllers in communication with two different sensors. As described above with respect to FIG. 2, thermostat controller 152 in communication with thermostat temperature sensor 150 comprises a feedback loop that attempts to maintain a nearly-constant space temperature at facility 108 by selectively attempting to turn load 114 on and off as needed.

However, referring to FIG. 13, during a load-control event, a second controller, controller 182 of comfort-optimizing LCD 118 communicates with comfort sensor 120 to form a second feedback loop 300 that attempts to maintain a measured comfort differential at or below a predetermined comfort differential by selectively disabling load 114.

FIG. 13 depicts a block diagram of a secondary negative feedback control system 300 of demand response system 100. At function 302, accomplished by LCD controller 182 in an embodiment, a maximum discomfort threshold, DT_(max), is compared to an actual or measured comfort indicator, such as an air temperature at return-air ducting 134 measured by comfort sensor 120. In an embodiment, the determined comfort indicator/temperature differential, ΔC_(actual) may be compared to a predetermined or maximum comfort differential ΔC, or an equivalent calculation may be made, to determine whether to actuate switching device 126, thereby disabling load 114. In the case of cooling, if ΔC_(actual) is greater than the maximum ΔC or the measured comfort indicator is greater than the maximum discomfort threshold, controller 182, the “controller output” does not disable load 114.

If thermostat controller 152 also outputs a COOL control signal as a controller output, then load 114 is activated, causing an energy transfer, followed by a further cooling/heating process 174. Comfort sensor 120 measures a comfort indicator of facility 108, and the negative-feedback cycle continues such that feedback loop 300 and system 100 continually strive to maintain a space temperature below a discomfort threshold.

The second feedback loop of comfort-optimizing LCD 118 may simplistically be modeled as one of the “disturbances” that influence the operation of first feedback loop 170 of thermostat 128.

Referring to FIGS. 14 a to 14 c, the effects of the comfort-based load-control modification as described with respect to FIG. 12 are depicted in a series of timing diagrams.

Referring specifically to FIG. 14 a, normal, non-controlled operation occurs from T₀ to T₅, followed by a first off-cycle (T₅ to T_(DT)) of a load-control event, and a first on cycle (T_(DT) to T₁₄) of the load-control event are depicted. During normal operation and during the on cycle, switching device 126 is closed, during the off cycle, switching device 126 is open.

Referring to FIGS. 14 b and 14 c, load 114 operates normally during the first on cycle, and a temperature sensed by comfort sensor 120 is maintained within the range of T_(sp+) and T_(sp−) by thermostat 128. At time T₅, the start of the off cycle, power to load 114 is interrupted, and sensed temperature begins to rise.

When the temperature sensed by comfort sensor 120 exceeds T_(DT), and in accordance with steps 248 to 254 of process 212 a (see FIG. 12), the off cycle is ended prematurely; comfort-optimizing LCD 118 causes switching device 126 to make, a COOL signal from thermostat 128 is transmitted, and reaches, control circuit 116, and load 114 is powered on.

During the on cycle, load 114 cools facility 108, sensed temperature falls to T_(sp−), and thermostat 128 ceases to transmit a COOL signal, subsequently causing load 114 to turn off at time T₁₄.

In an embodiment, and as depicted in FIG. 14 a the on cycle of the load-control cycle is simply lengthened, lasting from time T_(DT) to time T₁₆, such that the actual delivered duty cycle of switching device 126 is less than the original 50% duty cycle originally commanded by master controller 102, or approximately 40% (switching device open approximately 40% of load-control cycle, closed approximately 60% of load-control cycle).

In another embodiment, the off cycle is shortened as described, but rather than extending the subsequent on cycle such that it ends at the same time that it would have prior to modification, the on cycle lasts only as long as it would have prior to modification of the load-control event/cycle. In one such embodiment, an original duty cycle of 50% having an off cycle of 30 minutes followed by an on cycle of 30 minutes is modified such that the off cycle is 20 minutes, and the on cycle remains at 30 minutes (as opposed to an embodiment wherein the on cycle is extended to 40 minutes).

Consequently, by modifying the load-control event such that a comfort indicator does not exceed an individualized discomfort threshold, demand-response program participants that might otherwise become uncomfortable during a load-control event due to an under-capacity load 114 may remain satisfied.

Referring to FIG. 15 an embodiment of a process or algorithm 212 b (defining an embodiment of step 212 of FIG. 10) for modifying a load-control event so as to increase a space temperature toward a discomfort threshold, and/or above a minimum discomfort threshold is depicted and described. Such an embodiment may be appropriate for those program participants having over-capacity loads 114 that, as described above with respect to FIGS. 4 a-4 c and 6 a-6 c, and falling into Area C of FIG. 7, may never cause a comfort indicator to approach or exceed a discomfort threshold. For such participants, during a load-control event, the DR program causes little noticeable climatic change due to the relatively small demand reduction. Such participants and their HVAC systems 124 present an opportunity to capture additional energy savings.

At step 340, an off or shed cycle ends.

At step 342, an actual comfort indicator differential, ΔC_(Act), of the latest off cycle of the load-control event is determined by calculating the difference between the profiled interval value, PIV_(I) and the next measured, valid periodic comfort indicator data, CIV_(I):

ΔC _(Act)=PIV_(I)−CIV_(I)  Equation 7

Such a determination may be made by local LCD controller 182 or by a remote processor. ΔC_(ACT) may be an actual temperature differential.

At step 344 a target comfort indicator differential, ΔC_(Target) is determined. In an embodiment, the target comfort indicator differential, ΔC_(Target), is a predetermined, fixed number, such as a temperature differential. In one such embodiment, ΔC_(Target) ranges from 1° F. to 10° F.; in another such embodiment, ΔC_(Target) ranges from 0.25° F. to 5.00° F.; in another embodiment, ΔC_(Target) is 3° F. A predetermined value for ΔC_(Target) may be determined based on any number of factors, including knowledge of a capacity of an HVAC system 124, facility 108 characteristics, participant-provided information, and so on.

In other embodiments, the target comfort indicator differential, ΔC_(Target) is determined based on current and historical data obtained locally by system 100, and known load-control event parameters. In yet another embodiment, the target comfort indicator differential, ΔC_(Target) may be determined in any of the ways as described above with respect to the comfort differential, ΔC.

In an embodiment, ΔC_(Target) is defined by Equation 7 as follows:

ΔC _(Target) =ΔC _(Act)·(OC_(complete)/OC_(sched))  Equation 7

where OC_(complete) is defined as the number of off cycles completed and OC_(sched) is defined as the number of off cycles scheduled. The schedule number of off cycles is known based on the predetermined parameters of the load-control event, while the number of off cycles completed can be determined by comfort-optimizing LCD 118 or other local or remote processing capability. Calculating a per-cycle target comfort differential in this manner allows for a gradual ramping of the space temperature.

At step 346, the ratio of ΔC_(Act)/ΔC_(Target) is determined and compared to a predetermined value X. Such a predetermined value provides an indication of whether the actual comfort differential is moving toward the target comfort differential, and may be a value between 0 and 1 stored in firmware, or otherwise provided. If ΔC_(Act)/ΔC_(Target) is greater than X, the process ends and reverts to step 340. If ΔC_(Act)/ΔC_(Target) is less than X, indicating that the ratio is low and that the actual comfort differential is not approaching the target comfort differential, then the process proceeds to step 348.

At step 348, a boost time is determined. The boost time is the time period to add to the next off cycle to increase the actual comfort differential. In an embodiment, the boost time, T_(boost) is defined by Equation 8 as follows:

T _(boost)=(1−ΔC _(Act) /ΔC _(Target))·D _(exp oc)  Equation 8

where D_(exp oc) is defined as the expected off-cycle duration.

After step 348, the process reverts to step 340.

In a simpler, alternate embodiment, ΔC_(Target) is determined in any of the ways described above, and if ΔC_(Act) exceeds ΔC_(Target), an on-cycle may be skipped. In such an embodiment, the prior off-cycle may be repeated. This may continue until ΔC_(Act) is less than ΔC_(Target). This alternative embodiment is similar to the embodiment described above with respect to a comfort differential being greater than a target.

The embodiments above thusly include systems, devices and methods for retaining demand-response program participants, improving participant comfort levels, and optimizing energy savings.

The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the claims. In addition, although aspects of the present invention have been described with reference to particular embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention, as defined by the claims.

Persons of ordinary skill in the relevant arts will recognize that the invention may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the invention may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the invention may comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art.

Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.

For purposes of interpreting the claims for the present invention, it is expressly intended that the provisions of Section 112, sixth paragraph of 35 U.S.C. are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim. 

1-9. (canceled)
 10. A method of improving a comfort level of a participant in a demand-response program for a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device (LCD) in communication with a load of the HVAC system and an electrical utility provider, the method comprising: providing a sensor to a participant of a demand-response program, the sensor adapted to sense a comfort indicator at a facility, the comfort indicator including at least an air temperature; providing instructions for installing the sensor at a facility of the participant; and causing a load-control event communicated to the LCD to be modified at least in part in response to the comfort indicator as sensed by the sensor, the modification causing the comfort indicator to increase or decrease at the facility, thereby improving the comfort level of the participant in the demand-response program.
 11. A method of modifying a load-control event to maintain a space temperature at or below a discomfort threshold at a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device in communication with a load of the HVAC system and an electrical utility provider, the method comprising: monitoring a first space temperature with a thermostat having a first temperature sensor; obtaining first periodic comfort indicator data from a second temperature sensor sensing a comfort indicator, the comfort indicator including at least a temperature and obtained during a first predetermined time interval; determining a first profiled interval value for the first predetermined interval value, the first profiled interval value derived from the periodic comfort indicator data; obtaining second periodic comfort indicator data from the second sensor, the comfort indicator including at least a temperature and obtained during a second predetermined interval; determining whether the second periodic comfort indicator data exceeds a sum of the first profiled interval value and a comfort interval differential value; and causing a load of the HVAC system to receive a control signal from the thermostat prior to an expected termination of an off-cycle of a load-control cycle when the second periodic comfort indicator data exceeds a sum of the first profiled interval value and the comfort interval differential value, thereby modifying a load-control event.
 12. The method of claim 11, further comprising determining the comfort differential value.
 13. The method of claim 11, further comprising: providing a sensor to a participant of a demand-response program, the sensor for sensing a comfort indicator at a facility, the comfort indicator including at least an air temperature; and providing instructions for installing the sensor at a facility of the participant.
 14. A method of modifying a load-control event for a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device in communication with a load of the HVAC system and an electrical utility provider, the method comprising: determining a comfort profile for the facility, the comfort profile comprising an average profiled interval value; calculating a comfort differential value based on previously-measured climate data; receiving periodic comfort indicator data from a first sensor; and modifying a parameter of a predetermined load-control event communicated to a comfort-optimizing load-control device from an electrical utility provider when the periodic comfort indicator data exceeds a sum of the average profiled interval value and the comfort differential value.
 15. The method of claim 14, wherein calculating a comfort differential value based on previously-measured climate data comprises calculating a comfort differential value based on weather data.
 16. The method of claim 14, wherein calculating a comfort differential value based on previously-measured climate data comprises calculating a comfort differential value based on temperature data of the facility.
 17. A device for modifying a load-control event according to any of the methods of claims 11 and
 14. 18. A system for controlling a space temperature of a facility, comprising: an electrical load configured to receive power from a power distribution network of an electric utility provider; a control device in communication with the electrical load and configured to selectively cause the electrical load to receive the power from the power distribution network of the electric utility provider; a thermostat having a first controller and a first temperature sensor, the thermostat in communication with the control device of the electrical load and configured to control a temperature of the facility with a first feedback loop that includes the first temperature sensor sensing the facility temperature at a first location; and a comfort-optimizing load control device (LCD) having a second controller and in communication with a second temperature sensor, the LCD configured to influence the temperature of the facility with a second feedback loop that includes the second temperature sensor sensing the facility temperature at a second location.
 19. A method of improving a comfort level of a participant in a demand-response program for a facility having a heating, ventilating, and air-conditioning (HVAC) system and a communicative load-control device (LCD) in communication with a load of the HVAC system and an electrical utility provider, the method comprising: providing a sensor to a participant of a demand-response program, the sensor adapted to sense a comfort indicator at a facility, the comfort indicator including at least an air temperature, wherein the comfort indicator further includes a relative humidity; providing instructions for installing the sensor at a facility of the participant; and causing a load-control event communicated to the LCD to be modified at least in part in response to the comfort indicator as sensed by the sensor, the modification causing the comfort indicator to increase or decrease at the facility, thereby improving the comfort level of the participant in the demand-response program.
 20. The method of claim 19, further comprising calculating the relative humidity by measuring a dry-bulb temperature and a wet-bulb temperature and comparing the temperatures to determine the relative humidity.
 21. The method of claim 20, further comprising providing a processor to calculate an average temperature, relative humidity, and heat index for time intervals for developing a comfort profile comprising a data array of average comfort values.
 22. The method of claim 21, further comprising modifying a load-control event based on the comfort profile. 